1. Technical Field
The present disclosure generally relates to printed circuit boards (PCBs) and particularly, relates to a method for manufacturing a multilayer printed circuit board with plated through holes.
2. Description of Related Art
PCBs are widely used in most electronic devices for mounting electronic components and providing electrical connections. Improvements in electronic technology, means there is a special need for a high interconnection density and integrated multilayer printed circuit boards. Therefore, forming high precision interconnection plated through holes is a key process in manufacturing a multilayer PCB.
The plated through holes of the multilayer PCBs are generally formed by three steps. The first one is laminating at least two copper clad laminates into a multilayer substrate. The second one is forming a through hole by mechanical drilling process or by a laser ablation technology in the multilayer substrate with reference to an alignment mark such as a hole. The third step is forming a copper layer in the inner wall of the through hole by plating process creating a plated through hole. However, the at least two copper clad laminates will thermal expand after the laminating process, causing the alignment mark to shift from its initial location. As such, the plated through holes will have a bias error reference to its designed location. That leads a poor even failed interconnection in the multilayer substrate.
What is needed, therefore, is a method for manufacturing a multilayer printed circuit board to overcome the above-described problems.